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2007-01-01 - Colloque/Présentation - poster - Anglais - 1 page(s)

Callebaut Sophie, Gonon Maurice , Veys J.-N., "X-ray diffraction investigation of the anisotropic microstructure of cordierite honeycombs used for catalytic filters" in BCerS 06, Mol, Anvers, Belgique, 2006

  • Codes CREF : Matériaux céramiques et poudres (DI2744), Contrôle des matériaux (DI2830)
  • Unités de recherche UMONS : Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) Due to its low thermal expansion coefficient, cordierite is a ceramic exhibiting a high resistance to thermal shocks. This property is widely used in applications that require good thermo-mechanical properties, below 1000°C, at low cost. Cordierite can be produced by reactive sintering of raw materials as talc, natural and/or calcined kaolin, and alumina. During the synthesis, numerous parameters may influence the apparent expansion coefficient of the final ceramic [1-6]. Among these parameters, the size and shape of the raw materials particles in conjunction with the shaping process may lead to and orientation texture of the cordierite grains [4-6]. This work investigates the anisotropique microstructure of cordierite substrates used as catalyst support for automobile exhaust gas. These substrates present a honeycomb structure composed of a multitude of channels shaped by extrusion of a green pate. The first part of this work focuses on the role played by the raw materials on the preferential orientation of the cordierite crystals after firing. The investigations are performed by conventional XRD measurements, pole figures acquisitions and Rietveld refinement of XRD patterns on green and fired samples. For applications such as catalyst supports, the thermal expansion behaviour of the parts must be well controlled. In order to link the textured microstructure to the macroscopic anisotropic behaviour, the second part of this work investigated the thermal expansion coefficients of the cordierite unit cell. This is realised by high temperature XRD associated to Rietveld refinement. Those two points are then correlated in order to explain the anisotropique behaviour of the substrates.